There are many official ways how to update firmware on your Sony (Ericsson) XPERIA smartphone. You can use PC Companion or Sony Update Service on Windows computers or you can use Sony Bridge for Mac on Apple computers. But sometimes it is better to use unofficial way - you can get latest firmware as it's released for your country etc. Androxyde Flashtool is the best PC utility, which allows you to install new firmware, decrypt firmware files from Sony or relock bootloader on your phone. And it's available for Windows, Linux and Mac.

Androxyde Flashtool is very powerfull software, which allows you to make many advanced things with your phone.

Flashtool is a flashing software that can be used to:

Flash original Images (Android 1.6, 2.1, 2.3 Images)

Root your phone

Install Recovery, Busybox, custom kernels

Clean your Rom (remove /system/apps apps of your choice) (Be careful, unless you really know what you do, do not modify the default list. This can make your phone stuck at the SE Logo)

Clear dalvik cache

Optimize (install of JIT v2) (Disabled in 0.4, will readd it as a plugin for 2.1 phones only)

Customize (installs apps found in the custom/apps folder of the flashtool)

Clean uninstalled (remove any references to system apps removed in the Clean (root needed) step)

Firmware flashing

What do you need:

How to flash?

Run flashtool and click on the flash button

Choose "Flash mode", click "OK"

From the list on the left select firmware for flashing - BE CAREFUL, if you choose bad firmware you should brick your Xperia!

On the right side check "No final verification." If you want to delete your data, check both boxes with "Wipe.." If you want to flash only a part of firmware, use the "Exclude.." option in the middle. Don't use it if you don't know what are you doing!

Click "OK" and wait for instructions to connect your phone

Turn off your phone.

Connect your Xperia while holding the button from the list above. Make sure you're using button which you should use! Don't forget you're in flashmode! When the window disappears, release the button.

Wait until flashtool flashes your firmware. If there's not 100% in the progressbar, it's not done!

Disconnect your Xperia and turn it on (or make some other changes you want)

Kernel flashing

You can flash kernels with these extensions: .img, .elf or .sin. For flashing stock kernel use the guide above (for firmware flashing). Remember you need to download kernel file first. Kernels are NOT included in flashtool installation.